Triac dimmer circuits are commonly installed in homes and commercial establishments throughout the United States as they are inexpensive and efficient devices with which to effect lamp dimming. A triac dimmer installed in series with a power supply and an incandescent lamp in a light circuit controls how much power is delivered to a lamp and thereby how brightly the lamp shines. The triac dimmer cuts out a portion of the supplied AC power waveform, allowing only a portion of the supplied power to pass to the lamp, depending on the setting of the triac dimmer. In other words, the triac dimmer “chops” the supplied voltage. In an incandescent lamp, the thermal inertia of the glowing lamp filament smoothes the resulting pulses of power into a consistent light output consistent with the average power of the pulses. Thus, a user is able to dim an incandescent lamp to a desired brightness by adjusting the triac dimmer.
Modern energy efficient lighting systems are gradually supplanting the venerable incandescent lamp. Varieties of fluorescent and semiconductor lighting systems such as compact fluorescent lamps (CFLs) and light emitting diode lamps (LEDs) made in form factors and light outputs to function as replacement lamps for incandescent lamps, fitting into the same sockets with no more effort than is ordinarily required to change a light bulb. These modern replacement lamps are growing rapidly in popularity due to greatly increased energy efficiency and lamp life over that of the incandescent lamp.
However, the chopping action of a triac dimmer causes sharp transitions, or edges in the voltage of the AC power waveform. These changes, easily evened by thermal inertia in an incandescent lamp, may adversely affect the performance of modern energy efficient replacement lamps. The edges can cause the lamp to flicker, strobe, or dim inaccurately. Furthermore, the edges are harsh on the more complex circuits of modern energy efficient replacement lamps. Coupling a modern energy efficient lighting system with an AC dimming circuit may result in undesirable effects. Thus, modern energy efficient incandescent replacement lamps, such as CFLs and LEDs must contain circuitry adapted to handle the triac dimming waveform.